1. Field of the Invention
The present invention relates to a socket for a semiconductor device capable of selectively mounting one of a plurality of semiconductor devices, each having a different contour dimension from the other.
2. Description of the Related Art
Semiconductor devices to be mounted to electronic equipments are subjected to various tests prior to being actually mounted so that latent defects thereof are to be removed. Such tests are carried out in a non-destructive manner by the application of voltage stress, the operation in a hot environment or the hot holding in accordance with the thermal or mechanical environmental inspections. Of these tests, one effective for the removal of an integrated circuit having an infant mortality failure is a burn-in test as the operation test carried out for a predetermined period in a high-temperature condition.
A socket for a semiconductor device subjected to such a test is generally referred to as an IC socket which is disposed on a printed wiring board having an input/output section for receiving a predetermined test voltage into a semiconductor device to be tested and transmitting an abnormality detection signal representing a short-circuit or others generated from the semiconductor device as disclosed, for example, in Japanese Patent Application Laid-open No. 2001-185313.
As shown in FIG. 67, the socket for a semiconductor device includes a socket body 4 disposed on a printed wiring board not illustrated and accommodating a group of contact terminals (not shown) for the electric connection of a semiconductor device 2 with the printed wiring board, a positioning member 6 disposed above the contact terminal group within the socket body 4 and having an accommodating section 6a for mounting the semiconductor device 2 therein, a latch mechanism disposed around the positioning member 6 and having a pair of pressing members 8 for selectively holding the semiconductor device 2 relative to the accommodating section 6a of the positioning member 6, and a cover member 10 for transmitting the operative force via a drive mechanism to the latch mechanism 8 so that the pressing members 8 are operated.
The positioning member 6 is fixed to the socket body 4 so that the relative position of the terminals of the semiconductor device 2 to the contact terminal group is determined by locating the outer periphery of the semiconductor device 2 mounted within the accommodating section 6a at a desired position.
The pair of pressing members 8 of the latch mechanism are arranged opposite to each other while interposing the semiconductor device 2 between the both. The pressing member 8 comprises of a proximal end 8B supported rotational moveably by the socket body 4 and coupled to the above-mentioned drive mechanism, an touch portion 8P for selectively being in contact with or apart from the outer periphery of the semiconductor device 2, and a connecting portion 8C for coupling the proximal end 8B with the touch portion 8P.
When the semiconductor device 2 is mounted within the accommodating section 6a, the touch portion 8P of the pressing member 8 is located at a position in readiness apart from the accommodating section not to interfere with the semiconductor device 2, and after the semiconductor device 2 has been mounted in the accommodating section, the touch portion 8P of the pressing member 8 enters the accommodating section 6a as shown in FIG. 67 to occupy the holding position.
The cover member 10 has an opening 10a in a central area thereof for allowing the semiconductor device 2 to pass through the same when the semiconductor device 2 is mounted into or removed from the accommodating section 6a of the positioning member 6. The cover member 10 is adapted to be movable upward and downward to the socket body 10 and coupled to a drive mechanism (not shown). The drive mechanism may be, for example, a link mechanism or a cam mechanism for coupling the cover member 10 with the proximal end of the pressing member 8 in the latch mechanism to move rotationaly the pressing member 8 in accordance with the upward/downward motion of the cover member 10.
In such a construction, when the semiconductor device 2 is mounted into the accommodating section 6a of the positioning member 6 through the opening 10a of the cover member 10, it is possible to mount the semiconductor device 2 into the accommodating section 6a because the cover member 10 is pushed downward to be hold from the upper position at a predetermined stroke relative to the socket body 4 and the positioning member 6 to locate the touch portions 8P of the pair of pressing members 8 at the position in readiness apart from each other relative to the accommodating section 6a of the positioning member 6.
Then, if the cover member 10 is released from the holded state, the cover member 10 moves upward by a force of a biasing member not shown to the initial position and the touch portions 8P of the pressing members 8 move from the position in readiness relative to the accommodating section 6a of the positioning member 6 to be close to each other to press the terminals of the semiconductor device 2 located by the positioning member 6 toward the contact terminal group at the holding position. Accordingly, the semiconductor device 2 is held in the accommodating section 6a of the positioning member 6.
When semiconductor devices having various contour dimensions different from each other are tested by using the above-mentioned IC socket, it has been desired that one kind of the IC socket is commonly usable thereto and the more number of IC sockets are mounted at a higher density onto the printed wiring board.
However, since the number of IC sockets mounted onto one printed wiring board is as large as possible at present for the purpose of carrying out the burn-in test at a high efficiency, a mutual distance between the adjacent IC sockets is considerably small.
Under the present conditions, it may be thought to minimize a whole size of the IC socket for the purpose of increasing the number of IC sockets to be mounted. However, such a downsizing of the whole size of the IC socket has a limitation in view of the above-mentioned common use of one kind of the IC socket.